Control Device Illumination Homogeneity via Reflector and Cut-outs
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Solution Overview
Problem
Existing control devices for domestic appliances with touch switches face challenges in achieving homogeneous illumination due to the presence of electrical tracks on printed circuit boards, leading to high costs and energy consumption, and require transparent materials that are difficult to find for button panels that can carry electronic components.
Innovation Solution
A control device with a button panel featuring a half-shell reflector element and cut-outs that allow light to pass through, enabling homogeneous illumination without the need for transparent materials, and allowing the button panel to be used as a printed circuit board, reducing complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical tracks are provided on the printed circuit board for touch switch operation, then the touch switch can detect proximity or touch, but the illumination becomes non-uniform with dark areas where tracks are located
Solution Approach 1:
A light guide element is introduced as an intermediary component between the light source and the switchable area. This light guide redirects light paths to illuminate areas that would otherwise be blocked by electrical tracks, achieving uniform illumination across the entire switchable area while maintaining the integrity of the underlying circuit board and its electrical tracks.
2Illumination intensity
If transparent materials are used for the button panel to allow light transmission, then illumination can pass through, but suitable materials that are both transparent and able to carry electronic components are difficult to find and expensive
Solution Approach 1:
The button panel is segmented into two distinct functional layers: an opaque button panel for mounting electronic components and a separate light guide element for light transmission. This segmentation allows each layer to be optimized independently - the button panel can use standard opaque PCB materials while the light guide handles illumination functions, eliminating the need for expensive transparent materials that can carry electronics.
Solution Approach 2:
The button panel is designed to serve multiple functions simultaneously: it provides structural support, mounts electronic components, and defines the switchable areas, while the light guide element handles light transmission and distribution. This multi-functional design eliminates the need for specialized transparent materials.
3Device complexity
If a light source is mounted directly on the printed circuit board to illuminate the switch, then the structure is simple, but the illumination is non-uniform and some light is absorbed by the switchable area
Solution Approach 1:
A light guide element serves as a mediator between the simple light source mounting and the required uniform illumination. The light guide receives light from the simple mounted source and redistributes it uniformly across the switchable area, maintaining structural simplicity while achieving illumination uniformity.
4Illumination intensity
If the button panel is made transparent to allow light passage, then illumination can reach the switchable area, but the costs for transparent materials and printed circuit boards are high
Solution Approach 1:
The system is segmented into an opaque button panel and a separate light guide element. This allows the use of inexpensive opaque materials for the button panel while achieving light transmission through the light guide, significantly reducing material costs compared to using expensive transparent materials throughout.
Solution Approach 2:
The light guide element can be made from inexpensive materials and manufacturing processes, replacing the need for expensive transparent materials. This approach prioritizes cost-effective solutions over premium materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides aesthetically appealing, uniformly illuminated switchable areas with reduced costs and complexity, while allowing the button panel to function as a carrier for electronic components, enhancing the control device's functionality and durability.
Implementation Method 1
at least one light source element (24) arranged at a rear side of the button panel (22)... so that light through the button panel (22) can pass through the cut-out (12) out of the control device
Implementation Method 2
a reflector element (26) arranged behind the button panel (22) and behind the light source element (24)... providing a homogeneous illumination of at least a part of the switchable area
Data Source
Figure 1
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AI summary
The present invention relates to a control device, in particular for a domestic appliance. The control device comprises at least one front panel (10) and at least one button panel (22) arranged behind the front panel (10). The control device comprises at least one switch (20) being responsive to touching a switchable area on a front side of the front panel (10) in front of said switch (20) by a user. The switch (20) includes at least one light source element (24) arranged at a rear side of the button panel (22) and provided for illuminating the rear side of the front panel (10). The switch (20) includes at least one reflector element (26) arranged behind the button panel (22) and the light source element (24) and provided for reflecting the light from the light source element (24) to the rear side of the button panel (22). The button panel (22) includes at least one cut out (12, 14), wherein the cut-out (12, 14) corresponds with one switchable area of the switch (20) or more switchable areas of neighboured switches (20), so that the light can pass through the cut-out (12, 14) and the front panel (10) out of the control device. Further, the present invention relates to a button panel for said control device. Moreover, the present invention relates to a method for assembling the control device.